The invention relates to a wiping element made from a rubber-elastic or ductile-elastic material for the protection of components mobile against one another, at least one wiping lip being provided on the wiping element, wherein the wiping element has a protective lip, which is provided in a detachable fashion on the wiping element.
A wiping element of this kind has become known in the art for example by means of DE 86 15 170 U1. In order to seal an axially moving component such as a piston rod, a sealing lip and a wiping lip of the wiping element seats on that component. The sealing lip on the side of the medium wipes the film of medium located on the component during axial motion of that component. The side of the wiping lip exposed to atmosphere prevents the entrance of solid materials such as chips or soiling and their passage to the medium side. The additional protective lip can be removed but is otherwise connected to the wiping element in an integral manner to constitute a single unit, which can be installed. A holding edge of the protective lip is inserted or snapped into a support opening formed on the wiping element and is held on the mounted wiping element in this fashion. During use, the conventional wiping element seats with its protective lip on the component as a result of which impurities, in particular ice, can be scraped off.
US 2005/0067242 A1 concerns a sealing system for a shock absorber in a motor vehicle. A wiping element and a sealing element are disposed between a guiding rod and a piston rod in order to hold hydraulic liquid in the shock absorber and to prevent foreign particles as well as soiling from entering into the shock absorber. A wiping lip and a sealing lip of the wiping element seat on the piston rod. The side of the wiping element associated with the wiping lip has an associated protective lip, which is directed towards the outer side of the shock absorber. The protective lip is made from a hard plastic and engages at one end into a ring-shaped groove on the wiping element and, on the other end, seats on the piston rod for wiping off dirt, water, or foreign particles therefrom.
DE 44 08 408 C1 discloses a wiping element, which includes a wiping ring with a lip and a protective ring, which is integral with the wiping ring. The wiping element surrounds a piston rod and seats with its wiping lip on the piston rod to prevent the entrance of impurities in that soiling which adheres to the outer periphery of the piston rod is wiped off. In order to wipe off particles, which adhere more strongly to the piston rod, this wiping element can be equipped with an upstream protective lip made from a harder plastic material. During use, the protective lip of the wiping element also seats on the outer periphery of the piston rod. Projections are formed on the outer side of the wiping element for attachment of the protective lip which project through openings and recesses in the protective lip. The protruding end sections of the projections are preferentially re-formed into wide heads under the introduction of heat and constitute a rivet-like connection between the protective lip and the wiping element.
Wiping elements are used in systems of components mobile against one another in order to protect the latter against the entry of foreign substances. The wiping element is as a rule arranged upstream of a further seal. The wiping lip provided on the wiping element lies adjacent to the component which is exposed to the ambient conditions in the extended state and wipes off particles of dirt, ice, water and other foreign substances adhering to the component, before the component is retracted into the system again. In a cylinder-piston unit, the piston rod to be retracted is kept free from foreign substances by a wiping element. Wiping elements are described for example in the textbook “Heinz Konrad Müller, Abdichtung bewegter Maschinenteile, Medienverlag, 1990” (page 192) and are known as part of a wiper arrangement from DE 196 39 798.
The systems protected by wiping elements are often hydraulic. Foreign particles that have entered into a hydraulic system can lead to damage to seals, guides, valves and pumps. The components mobile against one another may also be damaged. The foreign particles can for example get under a downstream seal lying adjacent to a component under high pressure and, during the counter-movement of the components, damage at least one of the components. Furrows thus arise on the piston rod in a cylinder-piston unit during the retraction and extension of the piston rod. The furrows on the piston rod can in turn damage the wiping lip of a wiping element arranged upstream and thus impair the wiping element in its function.
The penetration of foreign substances is largely prevented by suitable wiping elements in the running operation of a hydraulic system. Damage and contamination on external areas of retracted components can however also occur before commissioning, in particular during transport and during assembly.
Systems of components mobile against one another such as a cylinder-piston unit are transported as a rule with a wiping element already assembled. For the purpose of protection against corrosion, the external area of a retracted component, for example the external piece of a piston rod, is wetted with wax or grease.
The components of a hydraulic system are as a rule painted after assembly. In the painting process, paint particles can get into the region of components whose surfaces are to be sealed against one another under high pressure. Due to temperature differences occurring in the course of the painting process, a component may be traversed to a differing extent against an adjacent component, as a result of which a drift area adjacent to the wiping element arises. The drift area of the component and the paint particles adhering to it are introduced into the hydraulic system following the painting process due to a cooling-related retraction of the component. The paint particles, like other foreign substances, have the initially described harmful effects on a hydraulic system. A hydraulic system can thus already be contaminated with foreign particles before commissioning, as a result of which the functionality of the wiping and sealing elements and the overall system may be impaired.
External areas of retracted components adjacent to the wiping element, in particular the drift area, are protected during painting with the aid of an upstream element, for example, an adhesive tape, a molded part or an O-ring. After the painting process, the protective devices are removed.
The problem underlying the invention is to protect, in a straightforward manner, external areas of a traversable component adjacent to a wiping element in a system of components mobile with respect to one another during transport and installation, wherein, in particular, the protective device can be easily removed.